#include <stdio.h>

#define PI 3.1415926
#define R 1

int main(void)
{
	double r, c, s;
	
	printf("Input the radius: ");
	scanf("%lf", &r);
#if R
	s = PI * r * r;
	printf("s = %.2f\n", s);
#else
	c = 2 * PI * r;
	printf("c = %.2f\n", c);
#endif

	return 0;
}